AD FAA-2013-0799

We are adopting a new airworthiness directive (AD) for certain ATR--GIE Avions de Transport R[eacute]gional Model ATR42 and Model ATR72 airplanes. This AD was prompted by reports of defective sealing between the nacelle lower fairing and the underwing box. This AD requires a one-time general visual inspection for damaged (worn, torn, or abraded) or missing seals between the nacelle lower fairing and the underwing box of both the left-hand and right-hand engine nacelles, and replacement of the seal and/or shims if necessary. We are issuing this AD to prevent the decrease of the fire extinguishing agent efficiency, which could delay fire extinction and allow fire propagation out of the nacelle fire protected area, resulting in damage to the airplane.